The present invention relates to an image forming apparatus equipped with an exposure member, which is movable toward and away from a photosensitive element.
Generally, in a known image forming apparatus, a photosensitive drum (photosensitive element) is electrically charged and this electrically charged photosensitive drum is then irradiated with light so that the electric potential of the irradiated area lowers to form an electrostatic latent image on the photosensitive drum. Thereafter, developer is supplied onto this latent image to form a developer image, which is then transferred onto a paper so that a predetermined image is formed on the paper.
As one example of such an image forming apparatus, Japanese Laid-open Patent Publication No. 2003-112446 discloses an image forming apparatus, which is equipped with an LED head for emitting light and irradiating a photosensitive drum with the light, and a top cover supporting the LED head and pivotally connected to the main body of the apparatus. In this image forming apparatus, opening the top cover causes the LED head to be retracted from the photosensitive drum, whereas closing the top cover causes the LED head to be positioned in a predetermined position with respect to the photosensitive drum.
Typically, the top cover is not required for positioning the LED head with respect to the photosensitive element. However, in this image forming apparatus disclosed in JP 2003-112446, the LED head is pressed and urged by the top cover toward the photosensitive element to carry out the positioning of the LED head. Therefore, the top cover does not provide a stable and accurate pressing force, which may result in a difficulty in accurate positioning between the LED head and the photosensitive element.
Further, it is difficult to effectively use the internal space of the image forming apparatus in which the LED head is supported by the pivotable top cover. This is because the moving passage (trajectory) of the LED head becomes longer and hence it is necessary to arrange the process unit, etc. so as not to cause interference with the LED head.
In view of the foregoing drawbacks of the prior art, the present invention seeks to provide an image forming apparatus in which accurate positioning of the exposure member to the photosensitive element is readily performed while the internal space of the apparatus can be used effectively.